1. Field of the Invention
The present invention relates to a power supply device and, more particularly, to a power supply device which can reliably perform data preservation even in the event of an unexpected power supply interruption in a medical device.
2. Description of the Related Art
It is necessary for a medical device to reliably preserve data obtained so far on a side of a product circuit (e.g., a processor) if supply of power to the device is interrupted.
For example, Japanese Patent Application Laid-Open Publication No. 2006-340921 proposes a technique in which turning off of a power switch triggers a process for an image pickup device, a display device, and the like of outputting an interruption signal for immediate stopping of power supply and a process for a processor of continuing supply of power to the processor for a fixed time period by generating an interruption signal which is delayed by the fixed time period in order to reliably implement data preservation at the time of a power supply interruption and interrupting the supply of power to the processor after a lapse of the fixed time period, when a power supply interruption occurs due to operation of a power switch in a power supply device which supplies power to a processor.
In Japanese Patent Application Laid-Open Publication No. 2006-340921, more specifically, a relay as an auxiliary switch is arranged in parallel with a power switch, and a delay circuit which keeps the relay on for a fixed period from when the power switch is turned off operates. Since supply of a commercial voltage into a processor is continued for the fixed time period after the power switch is cut off, a time period t1 required to reliably perform data preservation can be secured.